SABLE-3 Micro-Trak Tracker with
Trimble Lassen iQ GPS Receiver & Ultra Compact Embedded Antenna

A defective Sparkfun USB iQ evaluation board, with the USB connector and defective USB circuitry removed, was used as it was the quickest way to provide connections and a backup battery for the receiver.

Ceramic antennas, like the one used, work better with a ground plain and the thin 3" square piece of metal used for one provided a convenient way to install the GPS receiver and antenna into the lid of the payload container.

An area 1/4" smaller then the metal on 3 sides and 1/4" deep was cut from the center piece of the lid foam and the metal was slid into a slot cut along the bottom of the 3 cut sides until it was flush with the 4th open side. Another area the same size as the antenna, in the center of the first area and under the metal sheet was cut out for the antenna with a slot for the antenna feed-line to lay in as it runs to the receiver mounted on the opposite side of the metal with double sided foam tape.

The GPS receiver connected to the Micro-Trak which connects to a battery via the red & black leads for operation. The rough looking area in the lid and above the GPS receiver is an area cut out for the top of the camera to fit into. The box was filled with packing peanuts to keep the Micro-Trak & battery in place and masking tape was wrapped around the box to hold the top on. For programming the TinyTrak, no battery connection is required and the small USB serial port board is simply plugged into the Micro-Trak in place of the GPS receiver.

For details of the tracker, see the Micro-Trak 300 - V1.3 APRS Tracker page.

For more about the iQ GPS receiver, see the Lassen iQ GPS Receiver Page

See the SABLE Tracker Wiring & Modification Details PDF for wiring and further Micro-Trak, GPS & USB Board Details


Battery & Weight Data

Micro-Trak 300 Lassen iQ GPS Receiver
Typical Supply Voltage =
Minimum Supply Voltage =
Minimum Supply Voltage =
Idle Current (w/ No LEDs) =
Transmit Current =
 9.0 VDC
 6.6 VDC w/7805 reg.
 5.1 VDC w/ KF50BDT-TR reg.
  40 ma
134 ma
Supply Voltage =
Receiver + Antenna Current =
 3.3 VDC
 32.4 ma
( Receiver = 24.6 ma, Active Antenna = 7.8 ma )
3.3 VDC power is from a linear regulator on the
Micro-Trak powered from it's 5V linear regulator.

Total Tracker Current w/ GPS = 72.4 ma idle & 166.4 ma transmit for an avg. current of
≈74 ma when transmitting 1 sec/min. or ≈75.5 ma. when transmitting 2 sec/min.

5 Energizer L91 Lithium AA cells were used for power. The open circuit and loaded voltages weren't able to be measured until after the flight when the O.C. voltage was 9V, or 1.8V/cell. After 6-1/2 hrs of operation the loaded voltage was 7.79V and after 16 hrs was 7.62V, or 1.52V/cell. 5 cells were used to ensure there wouldn't be a problem, but 4 cells would have obviously been enough, would have lasted about 75 hrs. and have weighed only 13g more then an alkaline 9V battery that would have only lasted about 8 hrs. or until it froze, unlike the L91 AA Lithium/Iron Disulfide (Li/FeS2) cells which are good to −40C.

Tracker Weights
as used on SABLE-3
iQ GPS Receiver (7g),
GPS Antenna (10.6g),
GPS PCB, Battery & Wiring (11g),
3x3" Ground Plain (11.9g),
Micro-Trak 300 (18.5g)
VHF Antenna (68.5g)
5 cell battery w/ wire, etc. (85g)
Total Weight
= 212.5 g
A 4 cell battery would have saved 15g, but the antenna, although it's very good, weighs more then all of the other tracker items, as much as even a 4 cell battery and a much lighter antenna is definitely needed, even if not as good.


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